# 2.3 work and power problems pdf

```In class work work
1. The thrust (driving force) of an aircraft engine is 3.5 X 105 N. Calculate the work done by the
thrust when the aircraft travels 15 km.
2. A large box is pulled a distance of 8.5 m along a horizontal surface by a force of 50N that acts at
55&deg; to the horizontal. Calculate the work done by moving the box 8.0 m.
3. Fnd the work done on the object as show in the graph below :
4. Calculate the power in example 1, if the work is done for 5s.
5. Calculate the power in example 2, if the work is done for 35 s.
6. A new conveyor system at the local packaging plan will utilize a motor-powered mechanical arm
to exert an average force of 890 N to push large crates a distance of 12 meters in 22 seconds.
Determine the power output required of such a motor.
7. The Taipei 101 in Taiwan is a 1667-foot tall, 101-story skyscraper. The skyscraper is the home of
the world’s fastest elevator. The elevators transport visitors from the ground floor to the
Observation Deck on the 89th floor at speeds up to 16.8 m/s. Determine the power delivered by
the motor to lift the 10 passengers at this speed. The combined mass of the passengers and
cabin is 1250 kg.
8. A car is travelling at a constant speed of 15 ms-1 and its engine is producing a power output of
20kW. Calculate the force required to maintain the speed.
```